SCIENTIFIC RESOURCE CORE University of Rochester Paul D Wellstone MDCRC Repository and National Registry of Myotonic Dystrophy Patients and Family Members The last 5 years have brought remarkable progress in our understanding of the disease mechanisms in the myotonic dystrophies (DM1 &DM2). A relatively complete pathophysiologic understanding of these disorders is within reach, and new treatments that can reverse myotonia in animal models of DM1 are already available. To maximally exploit these research opportunities investigators need access to critical biological and bioinformatic resources and to patients willing to participate in clinical studies. To achieve these goals, we propose to combine our current Wellstone Center Repository Core and our NIH sponsored National Registry of Myotonic Dystrophy Patients and to enhance the resources of the Registry. The resources in the Repository include DM myoblasts, transgenic mouse models and cells derived from these models, plasmids for expressing expanded RNA repeats and for developing new models for repeat expansion disorders, antibodies, and tissue samples. During the currently funded operation many investigators outside of the URMC Wellstone MDCRC as well as within our Center have used Repository resources. A large database of information in carefully characterized DM1 patients is needed to identify optimal endpoints for treatment trials and develop better approaches for clinical care. To accomplish this goal we have included our National Registry of DM1 patients and family members which contains information on 676 DM patients and has 6 years of annual clinical data on 70% of the patients. The Registry is a major resource for recruitment for Project 1 in the renewal application and is a valuable resource to researchers within and outside of the Wellstone MDCRC network. We plan to recruit 80 Registry patients with DM1 for the studies of Project 1. Those patients will participate in the longitudinal clinical assessments of Project 1 that occur at 0, 12 and 36 months. These findings will enhance the value of their past and present information in the Registry. By helping to remove barriers to research, the Registry and Repository will improve the quality and quantity of research on DM and stimulate participation and involvement of new investigators, patients, family members, and care providers.